Base Transceiver Stations (BTS) provide wireless coverage in a particular area. The BTS may comprise of a plurality of transceivers, which transmit wireless communication signals to a plurality of users and receive wireless communication signals from the plurality of users. The users are present within the coverage area (also known as a cell) of the BTS.
In a wireless communication network with BTS, the BTS consume a large amount of energy; in some cases as high as 90% of the total consumption. The energy consumption of a BTS depends on the BTS hardware, the air interface technology, the size of the coverage area (which is defined in terms of cell radius) and the traffic load on the BTS (in terms of the users and their data rates). The optimal cell size from an energy perspective depends on all of the above factors. There is no fixed cell size that optimizes the overall energy consumption of a cellular network. Smaller cells may be efficient in terms of serving high capacity, but because of the fixed energy cost associated with keeping each BTS operational, they become less energy efficient when the demand is low. The demand for capacity as well as the user demography varies over time.
Currently there are mechanisms in use that can selectively turn off carriers in a BTS depending on the traffic load. Say, for a BTS with 3 carriers, during periods of low user activity when the current number of users and their demands can be met by a single carrier, two of the carriers can be switched off to save energy. But even when there are no active users, there are certain fixed costs involved with keeping the BTSs operational.